libceph: do not hard code max auth ticket len
authorIlya Dryomov <ilya.dryomov@inktank.com>
Tue, 9 Sep 2014 15:39:15 +0000 (19:39 +0400)
committerIlya Dryomov <ilya.dryomov@inktank.com>
Wed, 10 Sep 2014 16:08:36 +0000 (20:08 +0400)
We hard code cephx auth ticket buffer size to 256 bytes.  This isn't
enough for any moderate setups and, in case tickets themselves are not
encrypted, leads to buffer overflows (ceph_x_decrypt() errors out, but
ceph_decode_copy() doesn't - it's just a memcpy() wrapper).  Since the
buffer is allocated dynamically anyway, allocated it a bit later, at
the point where we know how much is going to be needed.

Fixes: http://tracker.ceph.com/issues/8979

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@redhat.com>
net/ceph/auth_x.c

index 0eb146d..de6662b 100644 (file)
@@ -13,8 +13,6 @@
 #include "auth_x.h"
 #include "auth_x_protocol.h"
 
-#define TEMP_TICKET_BUF_LEN    256
-
 static void ceph_x_validate_tickets(struct ceph_auth_client *ac, int *pneed);
 
 static int ceph_x_is_authenticated(struct ceph_auth_client *ac)
@@ -64,7 +62,7 @@ static int ceph_x_encrypt(struct ceph_crypto_key *secret,
 }
 
 static int ceph_x_decrypt(struct ceph_crypto_key *secret,
-                         void **p, void *end, void *obuf, size_t olen)
+                         void **p, void *end, void **obuf, size_t olen)
 {
        struct ceph_x_encrypt_header head;
        size_t head_len = sizeof(head);
@@ -75,8 +73,14 @@ static int ceph_x_decrypt(struct ceph_crypto_key *secret,
                return -EINVAL;
 
        dout("ceph_x_decrypt len %d\n", len);
-       ret = ceph_decrypt2(secret, &head, &head_len, obuf, &olen,
-                           *p, len);
+       if (*obuf == NULL) {
+               *obuf = kmalloc(len, GFP_NOFS);
+               if (!*obuf)
+                       return -ENOMEM;
+               olen = len;
+       }
+
+       ret = ceph_decrypt2(secret, &head, &head_len, *obuf, &olen, *p, len);
        if (ret)
                return ret;
        if (head.struct_v != 1 || le64_to_cpu(head.magic) != CEPHX_ENC_MAGIC)
@@ -131,18 +135,19 @@ static void remove_ticket_handler(struct ceph_auth_client *ac,
 
 static int process_one_ticket(struct ceph_auth_client *ac,
                              struct ceph_crypto_key *secret,
-                             void **p, void *end,
-                             void *dbuf, void *ticket_buf)
+                             void **p, void *end)
 {
        struct ceph_x_info *xi = ac->private;
        int type;
        u8 tkt_struct_v, blob_struct_v;
        struct ceph_x_ticket_handler *th;
+       void *dbuf = NULL;
        void *dp, *dend;
        int dlen;
        char is_enc;
        struct timespec validity;
        struct ceph_crypto_key old_key;
+       void *ticket_buf = NULL;
        void *tp, *tpend;
        struct ceph_timespec new_validity;
        struct ceph_crypto_key new_session_key;
@@ -167,8 +172,7 @@ static int process_one_ticket(struct ceph_auth_client *ac,
        }
 
        /* blob for me */
-       dlen = ceph_x_decrypt(secret, p, end, dbuf,
-                             TEMP_TICKET_BUF_LEN);
+       dlen = ceph_x_decrypt(secret, p, end, &dbuf, 0);
        if (dlen <= 0) {
                ret = dlen;
                goto out;
@@ -195,20 +199,25 @@ static int process_one_ticket(struct ceph_auth_client *ac,
 
        /* ticket blob for service */
        ceph_decode_8_safe(p, end, is_enc, bad);
-       tp = ticket_buf;
        if (is_enc) {
                /* encrypted */
                dout(" encrypted ticket\n");
-               dlen = ceph_x_decrypt(&old_key, p, end, ticket_buf,
-                                     TEMP_TICKET_BUF_LEN);
+               dlen = ceph_x_decrypt(&old_key, p, end, &ticket_buf, 0);
                if (dlen < 0) {
                        ret = dlen;
                        goto out;
                }
+               tp = ticket_buf;
                dlen = ceph_decode_32(&tp);
        } else {
                /* unencrypted */
                ceph_decode_32_safe(p, end, dlen, bad);
+               ticket_buf = kmalloc(dlen, GFP_NOFS);
+               if (!ticket_buf) {
+                       ret = -ENOMEM;
+                       goto out;
+               }
+               tp = ticket_buf;
                ceph_decode_need(p, end, dlen, bad);
                ceph_decode_copy(p, ticket_buf, dlen);
        }
@@ -237,6 +246,8 @@ static int process_one_ticket(struct ceph_auth_client *ac,
        xi->have_keys |= th->service;
 
 out:
+       kfree(ticket_buf);
+       kfree(dbuf);
        return ret;
 
 bad:
@@ -249,21 +260,10 @@ static int ceph_x_proc_ticket_reply(struct ceph_auth_client *ac,
                                    void *buf, void *end)
 {
        void *p = buf;
-       char *dbuf;
-       char *ticket_buf;
        u8 reply_struct_v;
        u32 num;
        int ret;
 
-       dbuf = kmalloc(TEMP_TICKET_BUF_LEN, GFP_NOFS);
-       if (!dbuf)
-               return -ENOMEM;
-
-       ret = -ENOMEM;
-       ticket_buf = kmalloc(TEMP_TICKET_BUF_LEN, GFP_NOFS);
-       if (!ticket_buf)
-               goto out_dbuf;
-
        ceph_decode_8_safe(&p, end, reply_struct_v, bad);
        if (reply_struct_v != 1)
                return -EINVAL;
@@ -272,22 +272,15 @@ static int ceph_x_proc_ticket_reply(struct ceph_auth_client *ac,
        dout("%d tickets\n", num);
 
        while (num--) {
-               ret = process_one_ticket(ac, secret, &p, end,
-                                        dbuf, ticket_buf);
+               ret = process_one_ticket(ac, secret, &p, end);
                if (ret)
-                       goto out;
+                       return ret;
        }
 
-       ret = 0;
-out:
-       kfree(ticket_buf);
-out_dbuf:
-       kfree(dbuf);
-       return ret;
+       return 0;
 
 bad:
-       ret = -EINVAL;
-       goto out;
+       return -EINVAL;
 }
 
 static int ceph_x_build_authorizer(struct ceph_auth_client *ac,
@@ -603,13 +596,14 @@ static int ceph_x_verify_authorizer_reply(struct ceph_auth_client *ac,
        struct ceph_x_ticket_handler *th;
        int ret = 0;
        struct ceph_x_authorize_reply reply;
+       void *preply = &reply;
        void *p = au->reply_buf;
        void *end = p + sizeof(au->reply_buf);
 
        th = get_ticket_handler(ac, au->service);
        if (IS_ERR(th))
                return PTR_ERR(th);
-       ret = ceph_x_decrypt(&th->session_key, &p, end, &reply, sizeof(reply));
+       ret = ceph_x_decrypt(&th->session_key, &p, end, &preply, sizeof(reply));
        if (ret < 0)
                return ret;
        if (ret != sizeof(reply))